500 likes | 1.19k Views
Electronic Cooling Solutions Inc. Thermal management consulting company Located in the heart of Silicon Valley Provide solutions for thermal design problems Use of experience, modeling & experimental methods in the design process Clients include over 60 companies. Outline. Introduction
E N D
Electronic Cooling Solutions Inc. • Thermal management consulting company • Located in the heart of Silicon Valley • Provide solutions for thermal design problems • Use of experience, modeling & experimental methods in the design process • Clients include over 60 companies
Outline • Introduction • Need for Innovative Cooling Solutions • Objective • Scope of this Presentation • Cooling Solutions – Air-based Cooling Systems • – Water-based Cooling Systems • – Refrigerant-based Cooling Systems • Comparative Analysis • Conclusion • Vendor Contacts
Introduction - Power Density and Heat Load Trends • Electrical Power = Waste Heat • Increase in power densities from the CPU-level to the System-level System-level Rack-level Board-level Component level Room-level • Current power density at the rack level = 1 to 3 kilowatts • (up to 30 kilowatts per rack in two to four years - Hannemann and Chu ‘07)
Need for Innovative Cooling Solutions at Rack-Level • Datacenter TCO is characterized on a per rack basis • Addition of newer and higher powered equipment in existing datacenters • Hotspots in datacenter resulting from high-density servers • Hotspots resulting from unavailability of cooling air from CRAC units • Design shortcomings within the rack result in inefficient cooling
Objective • Cooling of equipment in rack using airflow and impact of minor design changes for better cooling • Cooling of high density equipment using water-based cooling techniques • Cooling of high density equipment using refrigeration-based cooling techniques • Provide vendor data for the above mentioned products
Scope of this Presentation • Limited to discussion of cooling solutions only at the rack level • Closed racks and commercially available products • Discussion on Component-level, Board-level and Room-level cooling can be personally consulted
Cooling of Racks with Conditioned Air • Most easy to implement and maintain • Limitation based on cooling capacity, acoustics and power consumption • Detailed analysis could improve efficiency of air cooling Application of Computational Fluid Dynamics (CFD) • Pressure drops and airflow patterns • Determine by-pass air • Determine areas of re-circulation • Determine failure modes of cabinet fans • Requires testing to develop confidence in models
Cooling of Racks with Conditioned Air • Airflow Enhancement in Racks • Based on CFD Analysis • Sample case study 1 • Sample case study 2 • Cabinet powered fans – airflow layouts • Best practices • Airflow enhancing products
Sample Case Study 1 • Study done by Electronic Cooling Solutions Inc., • 42U Cabinet fitted with twenty one 2U units • 15.75 kilowatts per rack • Inlet temperature of 40 deg C • Airflow – 1932 CFM • 10,000 ft Altitude Conditions • Simplified cabinet shown here • Objective was to optimize the cabinet for better cooling/use of higher powered equipment
Sample Case Study 1 (Contd …) Higher temperatures at the inlet sides Inlet Temperature Re-circulation of Flow
Sample Case Study 1 (Contd …) • Added vertical blockages Open space between the rack rails and cabinet sides Vertical blockages between the rack rails and cabinet sides
Sample Case Study 1 (Contd …) • Added blockage above the topmost unit of the rack Top of 2U server Area above the topmost 2U rack is blocked Top of rack cover meant for passing cables from front to rear
Comparison of Inlet Temperatures Sample Case Study 1 (Contd …) No blockages Blocked passages
Sample Case Study 1 (Contd …) • Current study shows 17 to 25 % increase in power dissipation based on exhaust temperature. • By blocking re-circulating flow, it is possible to use higher powered equipment in the rack. • Blocking can be done by employing Brush Strips. • Avoid using larger racks with rails set to lower rack width settings (Using 23” rack with rails set to hold 19” equipment)
Sample Case Study 2 Container wall • Study done by Electronic Cooling Solutions Inc., • Racks placed in containers • Create airflow model of blowers • Evaluate alternate designs for blower module Heat Exchanger 2U Servers 2U Servers Blower Module Rack Model Symmetry Walls
Sample Case Study 2 Testing Module 1 – 860 CFM Module 2 – 1024 CFM • Apprx 20% increase in airflow with the re-designed baffles and perforated casing Testing to collect data for modeling
Cooling of Racks with Conditioned Air • Airflow Enhancement in Racks • Based on CFD Analysis • Sample case study 1 • Sample case study 2 • Cabinet powered fans – airflow layouts • Best practices • Airflow enhancing products
Ceiling Supply Air Raised Floor Front In – Top Out Airflow Enhancers – Cabinet Powered Fans Front or Footprint Inlet Supply Air Raised Floor Front In – Rear Out
Raised Floor Supply Air Airflow Enhancers (Cabinet Best Practices) Raised Floor Supply Air
Airflow Enhancers (Cabinet Best Practices (Contd…)) Dropped Ceiling Dropped Ceiling Raised Floor Raised Floor Supply Air Supply Air
Airflow Enhancing Products • APC 2U Rack Air Distribution • Delivers air directly from the raised floor into the rack inlet • Minimizes top-bottom inlet temperature distribution • Allows rack loads up to 3.5 kilowatts per rack Bottom-Top Rack Air Distribution Unit Side Rack Air Distribution Unit Roof Air Removal Unit Application View Images: APC (www.apc.com)
Airflow Enhancing Products (Contd…) Rittal Side Breathing Air Baffle System Rittal Enclosure Blower Images: Rittal (www.rittal-corp.com) • Higher density rear door rack air removal unit • Allows rack loads up to 16.5 kilowatts /14 kilowatts per rack • Challenges in obtaining flow through tiles in the datacenter Liebert XDA APC Images: www.apc.com and www.liebert.com
Water-based Cooling • Basis: QLOAD = mCpDT = rVCpDT • (Water has 3000 times higher heat carrying capacity than air) • Chilled water from building supply • Cooling high density servers up to 70 kilowatts per rack • Lower energy cost as some of the CRAC units can be removed • Avoid hotspots due to high power-density equipment • Possible to have redundant systems (Chillers, pumps, piping, and power supply) to avoid downtime • Importance of CDU • Electrically conductive, corrosiveness and high flow rates
Water-based Cooling Pure Water-based Cooling Combination of Air and Water Cooling Heat Exchanger Heat Exchanger Raised Floor Raised Floor
Water-based Cooling • Cooling system design by Naissus Thermal Management Solutions • Heat removal of 20+ kilowatts • Closed liquid loop with bottom mounted fin and tube heat exchanger • Thermal test done with 5 blade servers Water from Chiller Water sent to Chiller
Water-based Cooling Temperature Distribution inside the Rack
Water-based Cooling • Cooling system design by Vette Corp. • Heat removal of up to 30 kilowatts • Rear door closed loop liquid heat exchanger designed by IBM • Currently available only for IBM Enterprise Rack • Available from Rittal for retro-fit designs IBM Rear Door Heat Exchanger Images: www.vette-corp.com Pressure drop across the heat exchanger for a typical 1U fan setup
Water-based Cooling • Cooling system design by APC. • Heat removal of up to 70 kilowatts • Controlled in-row cooling • Row air containment • Modularity • Similar designs from HP (35 kilowatts) • Similar concepts available from Rittal (30 kilowatts) • Similar concepts available from Liebert (8 kilowatts and 17 kilowatts) Front View Rear View Heat Exchanger and Fan Assembly Images: www.apc.com
Refrigerant-based Cooling • Phase change (latent heat transfer) • Electronics-safe • Low flow rates and non-corrosive • Some systems are stand-alone and hence flexible • CRAC units are the most common ones • Chilled water from building supply may be used for supplemental cooling • Expensive ( comparable to water+ additives)
Refrigerant-based Cooling • Cooling system design by Liebert • XDF- Cooling capacity of 14 kilowatts • Stand-alone unit Liebert XDF Self Contained Unit Images: www.liebert.com
Refrigerant-based Cooling • Cooling system design by APC. • Heat removal of up to 43 kilowatts • Modularity • Rack air containment APC In-Row Cooling
Refrigerant-based Cooling • Cooling system design by Liebert • XDV- Rack mount air conditioners (10 kilowatts) - Almost no floor space required • XDH-Rack Cooling capacity up to 30 kilowatts • Also available from Rittal Liebert Roof Mount Cooling Liebert In-Row Cooling Rittal Rear Door Hx Images: www.liebert.com
Water/Refrigerant-based Touch Cooling • Direct contact cooling combined with chip cooling • Remove heat at the source • Available from: • Clustered Systems • Rittal (Power electronics) • SprayCool (20 to 30KW) Cold plate with Liquid Cooling Liquid Cooling of Boards Images: www.rittal-corp.com Images: www.ibm.com Spray Cooling Images: www.spraycool.com
Refrigerant-based Touch Cooling • Cooling system design by Thermal Form and Function • Pumped liquid multiphase cooling • Heat removal of up to 10 kilowatts • per evaporator (Modular) • Designed for retro-fit applications • Air/Water cooled condenser unit can be used Thermal Form and Function Refrigeration Unit Images: http://www.thermalformandfunction.com/ Two Phase Flow
Comparative Analysis • Study by Hannemann and Chu – Interpack ’07 • Comparative study of cooling technologies with a model datacenter Capital Expenditure of Cooling Equipment Area required for Cooling Equipment Power Consumption of Cooling Equipment
Conclusion • Reviewed innovative and commercially available technologies for cooling racks • Discussed design approaches with use of CFD to maximize performance of air cooling • Reviewed products and techniques for enhancing airflow within a rack • Reviewed cooling of high density equipment using chilled water and refrigerant • Selection of cooling strategy will depend on the specific requirements of the client
Vendor Contacts • APC – Morrison, Harold Wells Associates (925-355-9900) • Rittal – Sales (800-477-4000) • Liebert – Frank Stone (925-734-8660) • Spray Cool – Sales (866-993-2665) • Clustered Systems – Phil Hughes (415-613-9264) • Trox AITCS - Thomas Hudgens (347-325-4347) • Thermal Form and Function – Joe Marsala (978-526-9672) • Vette Corp - Skye Emerson (508-203-4694) • Naissus Thermal Management Solutions - Mirko Stevanovic (416-892-4071)
References • Product websites and communication with vendors • Hannemann, R and Chu, H., (2007), “Analysis of Alternative Data Center Cooling Approaches”, ASME Interpack 1176, Vancouver, BC.
Acknowledgement • Speck Design • Our colleagues at Electronic Cooling Solutions: • Khyati Varma • Ceferino Sanchez • Adriana Romero • Sridevi Iyengar